Improvements in semiconductor technology have contributed to a manyfold increase in the number of electronic devices used in everyday life. The reduced size and cost of transistors and integrated circuits have made many electronic devices virtual necessities to every day life. The expansion of electronic devices has occurred in the work place as well as the home, bringing people with virtually no electronic experience or skills into contact as purchasers and users.
There are two seemingly unrelated problems resulting from this expansion of electronics. First, there is an ever increasing problem of electromagnetic interference caused by such devices. Virtually every electronic device, intentionally or not, emits some form of electromagnetic radiation. While this condition could be tolerated when few devices existed, the increasing number of electronic devices has made the problem more acute. The problem has been exacerbated by the "improvement" in semiconductor devices which allows them to operate at higher speeds, generally causing emission in the higher frequency bands where interference is more likely to occur. Successful minimization of the interference problem, sometimes referred to as "electro-magnetic compatibility" or "EMC", generally requires that emissions from a given device be reduced by shielding and other means, and shielding be employed to reduce the sensitivity of a device to fields from other devices. Since shielding helps to reduce sensitivity to external fields as well as reduce emissions from the device, it is a common approach to a solution of the problem.
Another problem which has arisen with the reduced cost and size of customer/user to perform tasks which were formerly performed by highly skilled maintenance and service personnel. Today, when a computer is purchased it is not uncommon for the purchaser to literally carry it out of the store. This means that the set-up and installation of features must be done by the customer, who seldom has any specialized electronic skills. this situation mandates that the set-up and installation of features be very simple and virtually foolproof.
Looking now at the problems as they co-exist, it would be unrealistic to expect an unskilled user to be able to cope with the complex interlocking shielding or even fingerstock commonly used to achieve an adequate level of shielding. The prior art shielded enclosures have been designed for use by skilled technicians and often require the use of tools during installation and removal. Even further, even the plugging of circuit cards which contain upwards of twenty contacts is something not reliably accomplished by the unskilled user.
An additional problem is created when cables or supplementary or "add on" cards are to be connected to a system. Such devices commonly must be accurately plugged to avoid damage or improper operation of the system. The inadvertent unplugging of a cable while the system is in operation may create errors which completely disable the system.